I was pretty dehydrated one day, several month ago. I had a little bit of blood in my stream the next morning. Later at work I had a mildly burning peeing sensation at the urinal but very little came out. This sensation seemed to slowly move down the urethra and then a very small pile (almost like the spine on a dead animal carcass) came out like stacked stones or cairns. No severe pain, very mild; I was lucky.